1. Field of the Invention
This invention relates generally to fuel pressure-regulating valves, and more particularly to a fuel pressure-regulating valve for use in an electronic fuel injection system for internal combustion engines.
2. Description of the Prior Art
In an electronic fuel injection system for internal combustion engines, a fuel pressure-regulating valve generally regulates fuel pressure to the fuel injectors at a predetermined pressure level, and returns extra fuel to a fuel tank through a fuel return line. The regulating valve comprises a piston which is secured to a movable wall such as a diaphragm and is provided with a hollow stem. The hollow stem includes an aperture acting as a fuel passageway.
The regulating valve further comprises a bushing which is inserted securely in the hollow stem in order to ensure the movement of the piston in the axial direction. The bushing includes an aperture communicating with the fuel passageway in the hollow stem.
In a conventional fuel regulating valve, as described above, however, there is the drawback that a small displacement in the rotational direction may be produced between the piston and the bushing when the bushing is inserted into the hollow stem of the piston. As a result, the open area of the fuel passageway of the piston is reduced and the quantity of flow through the passageway decreases. Furthermore, when the regulating valve is employed in an electronic fuel injection system for internal combustion engines, it is difficult to ensure a constant air-fuel mixture, thus impairing the reliability of the regulating valve.